Application of unique measuring techniques to positive impulse corona stabilisation in SF6

Results of the application of unique measuring tools for corona stabilisation under positive impulse conditions in SF₆ are presented. The present postulate that corona stabilisation appears and disappears about a distinct threshold of impulse rise-time of approximately 10 μs is tested. For slow-rising impulses (>10 μs), breakdown is found to be able to occur both with and without corona stabilisation. The measurements are explained by the availability of free electrons during the rise-time of the impulse. The unique measuring tools applied rely on statistical analysis of records of the final spark path and correlation of this data with the time-to-breakdown data. The results of the measuring tools are initially verified through tests under conditions of known corona stabilisation